Viruses are short stretches of DNA or RNA, wrapped up in a protective protein coat. At least some sorts of virus are likely to be pieces of the genomes of other organisms, which have evolved the ability to move between cells. These are genes that have literally gained a life of their own.* Viruses are too short to encode all the proteins required for DNA replication (the shortest known virus, Porcine circovirus, is only 1,768 letters long). Rather than arranging its own replication, a virus hijacks host cells to do so. The host’s cellular machinery is used to copy the viral genome, and also to
...more
